What Makes Seat Belts, Air Bags Work For You

Click and Clack Talk Cars

April 22, 1993|By Tom and Ray Magliozzi, King Features Syndicate

QUESTION: I love your column, and I have two questions. 1) If you're sitting in the driver's seat in a parking lot with the engine off and you're hit head-on, will the air bag activate? 2) How can I check my seat belt to know for sure that it will hold me if I crash? I have tried to pull it as fast as possible, but it doesn't catch.

Dick

Tom: Good questions, Dick. Air bags need electricity to detonate. So most of them won't inflate when you're sitting in a parked car.

Ray: Here's how they work. When the ignition switch is on, the car's electrical system provides the power. When the car is shut off, electricity is stored for air bag detonation for between 30 seconds and several minutes, depending on the car. The reason for that is in an accident the battery connection could be severed early in the crash, and you'd still want the airbag to inflate seconds later and protect you.

Ray: As for the seat belt, the reason you can't get it to catch is because it doesn't respond to how fast you pull it, like seat belts used to in the '70s. Modern seat belts use a pendulum in the seat-belt housing at the bottom of the door frame. When the car stops suddenly, the pendulum swings forward and locks the belt. This design allows you to move comfortably at all other times and keeps you belted tightly in a panic stop or accident.

Tom: If you want to test the pendulum, go out to a parking lot, get going about 20 mph, and then brake hard. You should feel the belt lock as you're stopping.

Question: My 1986 Camry is coming up on 100,000 miles. Anything special I need to do?

Ray: Actually, Joyce, the one thing you should do is keep following the maintenance instructions in your owner's manual.

Tom: Most books have instructions that go though about 75,000 miles.

Ray: After that just put your car on a 60,000-mile cycle.

Tom: So when you get to 60,000, pretend you're starting at zero again (except for anything having to do with break-in, of course). That means you should do the ''30,000-Mile Service'' at 90,000 miles and the ''60,000-Mile Service'' at 120,000.

Question: I recently purchased a black Dodge Stealth, which I believe to be one of the finest cars on the road. I have taken a lot of flak from my friends about black cars being hotter than white cars. I personally checked the interior temperature of a black car against a white car in the same parking lot at the same time of day. Both cars had the same color interior, and the interior temperature was exactly the same in both vehicles. Do you know of any scientific studies which will substantiate my findings?

Louis

Tom: I suspect you're right, Louis. Everything we've heard about this subject tells us that black absorbs heat and white reflects it. But the only part of the car that could absorb heat and transmit it directly into the passenger compartment is the roof.

Ray: And I would guess that the amount of heat absorbed by the roof isn't enough to make any real difference. First of all, it's not that large an area. And second, there's insulation between the roof and the interior.

Tom: But the really interesting question is whether the interior color has any effect on interior temperature. And here's my boldest prediction of all . . . you ready for this?

Ray: Yeah. Wake me up when it's over.

Tom: I'll bet that the interior color of the car doesn't affect the temperature either!

Ray: That's your prediction, huh? Well, when the letters start pouring in from physics departments around the country, we'll see how much heat you generated with that answer.

Tom: Stay tuned. I can hardly wait!

Questions: The owner's manuals for my cars recommend 87 octane unleaded gas, which is available where I live. But when I'm on the road, ''regular unleaded'' is 85 octane, ''premium unleaded'' is 90, and there's no 87 available. I've noticed this especially in parts of Utah and Colorado. Which octane should I use?

Gus

Ray: The answer's simple, Gus. Use half and half in those situations. The gasoline you buy at the pump is a mixture of different octanes to begin with, so mixing 85 octane with 90 octane will work fine. You'll get 87.5 octane.

Ray: The reason the octane is lower in those areas is because they're at high altitudes, where the atmospheric pressure is lower. At lower pressure, you can get by with lower octane, which costs less and causes less pollution. Tom: So if you were going to stay in that area for a while, you could use 85 octane and your car would run fine. But if you're ''on the road'' and just passing through, use a mixture. Or, if that's too much trouble, be a big spender and splurge on the 90 octane.